1. Field of the Invention
The present invention relates to a turbine nozzle segment composing a part of a turbine nozzle to be installed onto the back of a turbine case of an aircraft engine.
2. Description of the Related Art
In the technical field of aircraft engines, a technique of dividing the turbine nozzle into a plurality of turbine nozzle segments has been widely employed because this enhances the high temperature strength, etc. of the turbine nozzle. Generally, the turbine nozzle segment comprises a plurality of stator vanes, an arc-like inner band integrally molded at the inner end of a plurality of the stator vanes, an arc-like outer band integrally molded at the outer end of a plurality of the stator vanes.
The concrete constitution of the inner band is as follows. An inner platform is formed at the inner end (on the hub side) of a plurality of the stator vanes, and the inner platform has a flange portion protruding inward at its back end and also has an inner flow-path face on its outer side. An inner leg is formed on the inner side of the inner platform, and the inner leg has a support arc at its inner end.
An outer platform is formed at the outer end (on the tip side) of a plurality of the stator vanes, and the outer platform has an outer flow-path face on its inner side. A forward outer leg is formed on the outer side of the outer platform, and the forward outer leg has, at its front end, a forward hook able to fit in an nozzle support hook of the turbine case. A aft outer leg is formed at the back of the forward outer leg on the outer side of the outer platform.
When the turbine nozzle assembly, which comprises a plurality of the turbine nozzle segments with the above constitution, is installed onto the back of the turbine case, the following operation will be performed using a assembly fixture. The assembly fixture is composed of the same number of inner lock pieces and outer lock pieces respectively as that of the turbine nozzle segments. That is to say, a plurality of the turbine nozzle segments are disposed in a circle to configure the turbine nozzle assembly.
By inserting and turning each inner lock piece of the assembly fixture in between the inner platform and the support arc of the turbine nozzle segment corresponding thereto, each inner lock piece is hooked on the flange portion corresponding thereto of the turbine nozzle segment. In a similar manner, by inserting and turning each outer lock piece of the assembly fixture in between the outer platform and the aft outer leg of the turbine nozzle segment corresponding thereto, each outer lock piece is hooked on the vicinity at the back end of the outer platform corresponding thereto of the turbine nozzle segment. Thereby, the turbine nozzle assembly can be temporarily loaded on the assembly fixture.
Then by making the assembly fixture approach to the back of the turbine case, the forward hook of the forward outer leg of each turbine nozzle segment is fit into the nozzle support hook of the turbine case. And then, the assembly fixture is separated from the turbine case by means of releasing the hooked state of each inner lock piece and the hooked state of each outer lock piece, respectively.